Spectrometry device, liquid chromatograph, and wavelength calibration method of spectrometer

Abstract

The wavelength of a spectrometer is calibrated by using a commercial Ho glass filter. The spectrometer includes a light source including a D 2 lamp and not including a mercury lamp, and a reference wavelength input unit for inputting, as a reference wavelength, a wavelength of a specific absorption peak separately measured for an Ho glass filter to be used. To calibrate the wavelength of the spectrometer by using the wavelength of a specific emission line peak of the D 2 lamp and the reference wavelength input by the reference wavelength input unit, the wavelength calibration unit holds a conversion table showing a theoretical relationship between the number of control pulses for rotating a diffraction element and the corresponding wavelength of diffracted light, and calibrates the number of control pulses from the conversion table by the wavelength calibration unit.

What is claimed is: 
     
       1. A spectrometry device comprising:
 a spectrometer including a diffraction element, a light source, including a D 2  lamp and not including a mercury lamp, for generating incident light for the diffraction element, a light detection element arranged at a position for receiving light dispersed by the diffraction element, and a wavelength drive unit to be controlled by a control pulse to rotate the diffraction element; 
 a filter attachment unit, in the spectrometer, for attaching an Ho glass filter in an attachable/detachable manner on a light path between the light source and the diffraction element; 
 a reference wavelength input unit for inputting, as a reference wavelength, a wavelength of a specific absorption peak separately measured for the Ho glass filter; and 
 a wavelength calibration unit including a conversion table holding unit for holding a conversion table showing a theoretical relationship between the number of control pulses for rotating the diffraction element and a corresponding wavelength of diffracted light, and a control pulse number calibration unit for calibrating the number of control pulses from the conversion table based on the number of control pulses n 01  that is the number of control pulses obtained from the conversion table and that corresponds to a wavelength of a specific emission line peak of the D 2  lamp, the number of control pulses n 02  that is the number of control pulses obtained from the conversion table and that corresponds to the reference wavelength input by the reference wavelength input unit, the number of control pulses n 1  before calibration at a time of detection of the emission line peak of the D 2  lamp, and the number of control pulses n 2  before calibration at a time of detection of the absorption peak of the Ho glass filter. 
 
     
     
       2. The spectrometry device according to  claim 1 ,
 wherein the wavelength calibration unit includes a D 2  emission line peak wavelength holding unit for holding the wavelength of the emission line peak of the D 2  lamp, and a reference wavelength holding unit for holding the reference wavelength input by the reference wavelength input unit, and 
 wherein the control pulse number calibration unit is configured to use, at a time of obtaining the number of control pulses from the conversion table, an emission line peak wavelength held by the D 2  emission line peak wavelength holding unit and the reference wavelength held by the reference wavelength holding unit. 
 
     
     
       3. The spectrometry device according to  claim 2 ,
 wherein the control pulse number calibration unit includes
 a shift amount calculation unit for calculating a first shift amount Δn 1  at the emission line peak wavelength based on the number of control pulses n 01 , in the conversion table, corresponding to the emission line peak wavelength and the number of control pulses n 1  before calibration at a time of detection of the emission line peak of the D 2  lamp, and for calculating a second shift amount Δn 2  at the reference wavelength based on the number of control pulses n 02 , in the conversion table, corresponding to the reference wavelength and the number of control pulses n 2  before calibration at a time of detection of the absorption peak, and 
 a shift amount holding unit for holding the shift amounts Δn 1  and Δn 2  calculated by the shift amount calculation unit, and 
 
 wherein the wavelength drive unit is configured to rotate the diffraction element based on, at a time of wavelength calibration, the number of control pulses in the conversion table held by the conversion table holding unit, and at a time of sample measurement, the number of control pulses after wavelength calibration that is the number of control pulses held by the conversion table holding unit after correction based on the shift amounts Δn 1  and Δn 2  held by the shift amount holding unit. 
 
     
     
       4. The spectrometry device according to  claim 1 ,
 wherein the control pulse number calibration unit includes
 a shift amount calculation unit for calculating a first shift amount Δn 1  at the emission line peak wavelength based on the number of control pulses n 01 , in the conversion table, corresponding to the emission line peak wavelength and the number of control pulses n 1  before calibration at a time of detection of the emission line peak of the D 2  lamp, and for calculating a second shift amount Δn 2  at the reference wavelength based on the number of control pulses n 02 , in the conversion table, corresponding to the reference wavelength and the number of control pulses n 2  before calibration at a time of detection of the absorption peak, and 
 a shift amount holding unit for holding the shift amounts Δn 1  and Δn 2  calculated by the shift amount calculation unit, and 
 
 wherein the wavelength drive unit is configured to rotate the diffraction element based on, at a time of wavelength calibration, the number of control pulses in the conversion table held by the conversion table holding unit, and at a time of sample measurement, the number of control pulses after wavelength calibration that is the number of control pulses held by the conversion table holding unit after correction based on the shift amounts Δn 1  and Δn 2  held by the shift amount holding unit. 
 
     
     
       5. The spectrometry device according to  claim 1 ,
 wherein the control pulse number calibration unit includes
 a shift amount calculation unit for calculating a first shift amount Δn 1  at the emission line peak wavelength based on the number of control pulses n 01  , in the conversion table, corresponding to the emission line peak wavelength and the number of control pulses n 1  before calibration at a time of detection of the emission line peak of the D 2  lamp, and for calculating a second shift amount Δn 2  at the reference wavelength based on the number of control pulses n 02 , in the conversion table, corresponding to the reference wavelength and the number of control pulses n 2  before calibration at a time of detection of the absorption peak, 
 a conversion table correction unit for calibrating the number of control pulses in the conversion table by the shift amounts Δn 1  and Δn 2  calculated by the shift amount calculation unit, and 
 a calibrated conversion table holding unit for holding a calibrated conversion table calibrated by the conversion table correction unit, and 
 
 wherein the wavelength drive unit is configured to rotate the diffraction element based on, at a time of wavelength calibration, the number of control pulses in the conversion table held by the conversion table holding unit, and at a time of sample measurement, the number of control pulses in the calibrated conversion table held by the calibrated conversion table holding unit. 
 
     
     
       6. The spectrometry device according to  claim 2 ,
 wherein the control pulse number calibration unit includes
 a shift amount calculation unit for calculating a first shift amount Δn 1  at the emission line peak wavelength based on the number of control pulses n 01 , in the conversion table, corresponding to the emission line peak wavelength and the number of control pulses n 1  before calibration at a time of detection of the emission line peak of the D 2  lamp, and for calculating a second shift amount Δn 2  at the reference wavelength based on the number of control pulses n 02 , in the conversion table, corresponding to the reference wavelength and the number of control pulses n 2  before calibration at a time of detection of the absorption peak, 
 a conversion table correction unit for calibrating the number of control pulses in the conversion table by the shift amounts Δn 1  and Δn 2  calculated by the shift amount calculation unit, and 
 a calibrated conversion table holding unit for holding a calibrated conversion table calibrated by the conversion table correction unit, and 
 
 wherein the wavelength drive unit is configured to rotate the diffraction element based on, at a time of wavelength calibration, the number of control pulses in the conversion table held by the conversion table holding unit, and at a time of sample measurement, the number of control pulses in the calibrated conversion table held by the calibrated conversion table holding unit. 
 
     
     
       7. A liquid chromatograph comprising:
 a delivery unit, arranged at an upstream end of a flow path through which a mobile phase is to flow, for supplying the mobile phase; 
 a sample injection unit for injecting a sample into the flow path; 
 a separation column arranged downstream of the sample injection unit; 
 a flow cell, arranged downstream of the separation column, through which an eluate from the separation column is to flow; and 
 the spectrometry device according to  claim 1 , the spectrometry device being arranged to optically detect the eluate flowing through the flow cell, the flow cell being arranged on a light path from the diffraction element to the light detection element at the spectrometer. 
 
     
     
       8. A liquid chromatograph comprising:
 a delivery unit, arranged at an upstream end of a flow path through which a mobile phase is to flow, for supplying the mobile phase; 
 a sample injection unit for injecting a sample into the flow path; 
 a separation column arranged downstream of the sample injection unit; 
 a flow cell, arranged downstream of the separation column, through which an eluate from the separation column is to flow; and 
 the spectrometry device according to  claim 2 , the spectrometry device being arranged to optically detect the eluate flowing through the flow cell, the flow cell being arranged on a light path from the diffraction element to the light detection element at the spectrometer. 
 
     
     
       9. A liquid chromatograph comprising:
 a delivery unit, arranged at an upstream end of a flow path through which a mobile phase is to flow, for supplying the mobile phase; 
 a sample injection unit for injecting a sample into the flow path; 
 a separation column arranged downstream of the sample injection unit; 
 a flow cell, arranged downstream of the separation column, through which an eluate from the separation column is to flow; and 
 the spectrometry device according to  claim 3 , the spectrometry device being arranged to optically detect the eluate flowing through the flow cell, the flow cell being arranged on a light path from the diffraction element to the light detection element at the spectrometer. 
 
     
     
       10. A liquid chromatograph comprising:
 a delivery unit, arranged at an upstream end of a flow path through which a mobile phase is to flow, for supplying the mobile phase; 
 a sample injection unit for injecting a sample into the flow path; 
 a separation column arranged downstream of the sample injection unit; 
 a flow cell, arranged downstream of the separation column, through which an eluate from the separation column is to flow; and 
 the spectrometry device according to  claim 4 , the spectrometry device being arranged to optically detect the eluate flowing through the flow cell, the flow cell being arranged on a light path from the diffraction element to the light detection element at the spectrometer. 
 
     
     
       11. A wavelength calibration method for calibrating a wavelength of a spectrometer including a diffraction element, a light source for generating incident light for the diffraction element, a light detection element arranged at a position for receiving light dispersed by the diffraction element, and a wavelength drive unit for rotating the diffraction element with respect to an incident direction of the incident light based on the number of control pulses, the method comprising the steps of:
 attaching an Ho glass filter, in the spectrometer, on a light path between the light source and the diffraction element; 
 setting an Ho absorption peak wavelength separately measured for the Ho glass filter as a reference wavelength; 
 holding a conversion table showing a theoretical relationship between the number of control pulses for rotating the diffraction element and a corresponding wavelength of diffracted light; and 
 calibrating the number of control pulses from the conversion table based on the number of control pulses that is the number of control pulses obtained from the conversion table and that corresponds to a wavelength of a specific emission line peak of a D 2  lamp, the number of control pulses that is the number of control pulses obtained from the conversion table and that corresponds to the reference wavelength, the number of control pulses before calibration at a time of detection of the emission line peak of the D 2  lamp, and the number of control pulses before calibration at a time of detection of the absorption peak of the Ho glass filter, 
 wherein the light source including a D 2  lamp and not including a mercury lamp is used.